JP2009281426A - Lock nut - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lock nut correcting deformation such as bending of a spindle in a high-speed rotating region and contributing to reduction in vibration and noise of the spindle. <P>SOLUTION: When balance adjustment set screws 46 are fitted to a plurality of balance adjustment screw holes 38, rotating balance of the spindle 50 is adjusted, and looseness in the radial direction of a rotating system including the spindle 50 is prevented. When vibration damping screw plugs 48 are fitted to the balance adjustment screw holes 38 to which the balance adjustment set screws 46 have been already fitted, in cooperation with the balance adjustment set screws 46 and the vibration damping screw plugs 48, the vibration of the rotating system is further reduced. In addition, since the balance adjustment screw holes 38 are closed by the vibration damping screw plugs 48, noise generation due to wind noise is reduced to reduce noise during rotation of the spindle 50, compared to the case where the balance adjustment screw holes are not closed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lock nut, a high-speed machining center, a high-speed NC lathe, a multi-tasking machine such as a 4-axis machine, a 5-axis machine, etc., and a positioning that corrects parallelism, deflection, etc. The present invention relates to a lock nut that is used as a part, and that particularly positions and fixes a fixed member such as a bearing attached to the main shaft.

Conventionally, for example, as a spindle device of a machining center, a hollow spindle with a tool attached to the tip, and the spindle does not rotate with respect to the spindle but is arranged on the same axis as the spindle so as to be movable in the axial direction. In addition, there has been known one provided with a draw bar for attaching / detaching a tool to / from the spindle end by movement in the axial direction.
In such a spindle device, since it is inevitable that there is a gap between the inner peripheral surface of the main shaft and the outer peripheral surface of the draw bar, when the rotation system including the main shaft and the draw bar is rotated, the draw bar Therefore, the center of gravity deviates in the radial direction and deviates from the axis of rotation of the main shaft. Therefore, there has been a problem that the center of gravity of the rotating system deviates from the axis of rotation of the main shaft and vibration occurs during rotation, resulting in a decrease in machining accuracy.
For this reason, conventionally, the balance of a main spindle of a machine tool that rotates at high speed is usually corrected to reduce vibration of the main spindle. The main shaft rotation balance can be adjusted by placing the main shaft on a balancing device and measuring the rotation balance of the main shaft while providing a hole in a required portion of the main shaft or grinding the relevant portion to balance the main shaft. It was a correction. In this case, the rotation balance adjustment of the main shaft is adjusted in the state of the main shaft alone before assembling the main shaft head.
However, in such adjustment of the rotation balance of the main spindle alone, even if the rotation balance of the main spindle is adjusted, other components incorporated into the main spindle, for example, a bearing that rotatably supports the main spindle and the bearing are positioned. The imbalance of parts such as lock nuts to be fixed could not be adjusted. Therefore, in a high-speed rotation speed region exceeding 10,000 revolutions per minute, for example, 10,000 rpm to 30,000 rpm, the vibration of the main shaft is increased due to imbalance of other components incorporated into the main shaft.
In view of this, a rotation balance adjustment method for machine tools suitable for adjusting the rotation balance of the spindle of a machine tool that is rotated at a high rotation speed has been proposed (see, for example, Patent Document 1). That is, a plurality of screw holes are formed at both ends of the main shaft, and after inserting a test weight with the weight adjusted in this screw hole with the draw bar, disc spring, and motor rotor assembled, the main shaft is rotated. The rotation angle and vibration amplitude of the spindle are measured, and the rotation balance of the spindle is adjusted based on the measurement results. In this case, a collar is attached to one end of the draw bar, and a nut in which a screw hole for balance adjustment is formed is screwed.
In this conventional rotational balance adjusting method, the rotational balance of the main shaft can be adjusted in a state where the main shaft is assembled.

JP-A-6-126588

However, recently, in order to further improve the machining efficiency, the spindle of the machine tool tends to be rotated at a higher rotational speed, and this tendency is expected to increase further in this case. It is considered that there is a demand for reduction in vibration and noise reduction of the spindle of the machine tool in a high rotational speed region exceeding 30,000 rpm to 50,000 rpm, for example.
However, in such a high-speed rotation speed region, deformation such as deflection occurs in the main shaft, and it is expected as a problem that vibration of the main shaft increases due to unbalance due to deformation of the main shaft.
Further, according to the above-described prior art, it is also expected that noise is generated in the main shaft rotating in the high speed rotation speed region due to wind noise caused by the screw hole for balance adjustment when the main shaft rotates.
Therefore, in view of the circumstances described above, the inventor of the present application has devised the present invention by paying attention to a lock nut used as a positioning component for correcting deformation such as parallelism of the main shaft and deflection in a high-speed rotation speed region. .

  That is, a main object of the present invention is to provide a lock nut that corrects deformation such as deflection of the main shaft in a high-speed rotation speed region and contributes to lower vibration and lower noise of the main shaft.

The present invention according to claim 1 is a lock nut that is screwed into a male screw portion of a main shaft of a machine tool and positions and fixes a fixed member attached to the main shaft, and the male screw portion of the main shaft and a screw are formed on the inner peripheral surface thereof. A lock nut body having a female thread portion to be joined, a seat surface formed on one end side in the axial direction of the lock nut body, and pressing the fixed member in the axial direction of the main shaft, and the other end side in the axial direction of the lock nut body A plurality of balance adjustment members arranged at predetermined intervals in the circumferential direction of the top surface of the lock nut body and extending in the axial direction of the lock nut body from the top surface. It is installed in the screw hole and the screw hole for balance adjustment from the top side of the lock nut body, and the balance adjustment set screw that adjusts the rotation balance of the spindle and the balance adjustment set screw that is equipped with the balance adjustment set screw Flip the holes, is mounted so as to close the screw holes for balancing, characterized in that it comprises a damping screw plugs to reduce vibrations during rotation of the main shaft, a lock nut.
In the present invention according to claim 1, the balance adjustment set screw is attached to the plurality of balance adjustment screw holes to prevent the rotation system including the main shaft from rattling in the radial direction, and the rotation balance of the main shaft. Is adjusted. That is, the balance adjusting set screw corrects the deviation of the center of gravity of the rotating system including the main shaft from the main shaft rotation center axis. In this case, among the plurality of balance adjustment screw holes, the balance adjustment screw hole is located in the opposite direction to the direction in which the center of gravity of the rotation system including the main shaft is shifted across the rotation center axis of the main shaft. It is preferable that the shift of the center of gravity of the rotating system including the main shaft from the main shaft rotation center axis is corrected by mounting the set screw.
Further, when a vibration control screw plug is attached to the balance adjustment screw hole in which the balance adjustment set screw is already attached, vibration during rotation of the spindle is further suppressed. That is, the vibration of the rotating system including the main shaft is further reduced by the cooperative action of the balance adjusting set screw and the damping screw plug. In this case, the balance adjustment screw hole is closed by a vibration control screw plug and is closed by a so-called plug, so that noise caused by wind noise is higher than that in a non-closed state. The generation of noise is reduced, and the noise during rotation of the spindle can be reduced.
The present invention according to claim 2 is characterized in that the rotation balance of the main shaft is adjusted by positioning and fixing the fixed member attached to the main shaft by the lock nut according to claim 1. It is a balance adjustment structure.
In the present invention according to claim 2, the fixed member such as a bearing that rotatably supports the main shaft can be positioned and fixed using the above-described lock nut, so that the rotation balance of the rotating system including the main shaft is appropriately adjusted. It is possible to adjust.

  According to the present invention, it is possible to obtain a lock nut that corrects the bending deformation of the main shaft in the ultra-high rotational speed region and enables the vibration and noise reduction of the main shaft.

  The above object, other objects, features, and advantages of the present invention will become more apparent from the following description of the best mode for carrying out the invention with reference to the drawings.

FIG. 1 is an essential part sectional view showing an example of an embodiment of the present invention, FIG. 2 is an enlarged view showing the details of part A of FIG. 1, and FIG. FIG. 3B is a perspective view of the vibration control screw plug, and FIG. 5A is a front view of the lock nut body. FIG. 5B is a cross-sectional view taken along the line B-B in FIG. 5A, and FIG. 5C is a cross-sectional view taken along the line C-C in FIG.
As shown in FIG. 1, for example, the lock nut 10 according to the present embodiment is screwed into a male screw portion 50 </ b> A of a main shaft 50 of a machine tool and attached to the main shaft 50, and the main shaft 50 is fixed to a predetermined position in the housing 70. The bearing 60 (fixed member) that is rotatably supported is fixedly positioned.

  For example, as shown in FIGS. 4 and 5, the lock nut 10 includes a cylindrical lock nut main body 14 having an internal thread portion 12 on the inner peripheral surface thereof. The lock nut body 14 has a seat surface 16 formed on one end side in the axial direction and a top surface 18 formed on the other end side in the axial direction. The seating surface 16 is formed, for example, as a pressing surface that presses the bearing 60 shown in FIG. 1 from the axial direction of the main shaft 50.

The lock nut main body 14 includes a ring-shaped groove 20 that is orthogonal to the axial direction of the lock nut main body 14, for example, as shown in FIGS. 4 and 5 (B) and (C). The female screw portion 12 of the lock nut main body 14 has a ring-shaped groove portion 20 and a second lock on the side of the top surface 18 having the first female screw portion 12b and the first lock nut portion 22 on the seat surface 16 side having the first female screw portion 12a. The female screw portion 12 of the lock nut main body 14 is divided into a first female screw portion 12a on the seat surface 16 side and a second female screw portion 12b on the top surface 18 side. In this case, the length of the 1st female thread part 12a is formed longer than the length of the 2nd female thread part 12b. That is, the number of threads of the first female thread portion 12a is formed to be larger than the number of threads of the second female thread portion 12b.
In this case, according to the inventor's load test, the greater the number of threads of the first female thread 12a than the number of threads of the second female thread 12b, the greater the force withstanding the axial load. Has been demonstrated. Further, in the lock nut main body 14, the female thread 12 is divided into the first female thread 12a and the second female thread 12b by the ring-shaped groove 20, and the length of the second female thread 12b is the first female thread. When the lock nut main body 14 is pushed into the main shaft 50 by applying a specified tightening torque (see, for example, FIG. 1), the thread of the second female thread portion 12b is deformed. Becomes larger. Therefore, in this lock nut main body 14, the surface pressure with respect to the male screw part 50A of the main shaft 50 by the flank surface of the second female screw part 12b is increased, and the locking action between the female screw part 12 of the lock nut main body 14 and the main shaft 50 is further increased. Demonstrated.

The first lock nut portion 22 includes an annular slit groove portion 26 disposed in a direction orthogonal to the axial direction of the lock nut main body 14 from a position near the ring-shaped groove portion 20 on the outer peripheral surface thereof. The slit groove 26 extends from the outer peripheral end surface of the first lock nut portion 22 to the vicinity of the second female screw portion 12b. Further, the first lock nut portion 22 has a plurality of fool holes 28 at a predetermined interval in the circumferential direction of the outer peripheral surface thereof. These fool holes 28 are for engaging a dedicated spanner (not shown) such as a hook spanner used when the lock nut body 14 is attached to the main shaft 50 shown in FIG.
A plurality of fool holes 30 having the same function are also disposed on the top surface of the second lock nut portion 24. In particular, as shown in FIG. 4 and FIG. 5B, the plurality of fool holes 30 are arranged at predetermined intervals in the circumferential direction of the top surface of the lock nut body 14. In the present embodiment, for example, each of the six holes 28 and the three holes 30 are formed.

Further, the lock nut main body 14 has a plurality of screw holes 32 for tightening at a predetermined interval in the circumferential direction of the seat surface 16. Each tightening screw hole 32 extends in the axial direction of the lock nut body 14 and extends from the side end surface of the first lock nut portion 22 (seat surface 16 of the lock nut body 14) to the slit groove portion 26. ing.
On the other hand, on the top surface 18 of the lock nut main body 14, a plurality of tightening insertion holes 34 are disposed at portions facing the respective tightening screw holes 32. The plurality of tightening insertion holes 34 are arranged at predetermined intervals in the circumferential direction of the top surface 18, and are respectively arranged from the side end surface of the first lock nut portion 22 (the top surface 18 of the lock nut body 14). The slit groove 26 is reached via the ring-shaped groove 20. Each of the plurality of tightening insertion holes 34 has a counterbore hole 36 near the top surface 18 into which a head 42 of a tightening set screw 40 to be described later enters.
The above-described tightening screw holes 32 and the respective tightening insertion holes 34 are arranged on the same axis and connected to each other, and a tightening set screw 40 described later is inserted from the tightening insertion hole 34. The screw hole 32 for tightening is screwed. In the present embodiment, for example, a plurality of screw holes 32 for fastening and six insertion holes 34 for fastening are each formed, for example.

  Furthermore, the lock nut main body 14 has a plurality of screw holes 38 for balance adjustment at predetermined intervals in the circumferential direction of the top surface 18. The plurality of balance adjusting screw holes 38 are respectively provided so as to extend in the axial direction of the lock nut body 14, and from the side end surface of the second lock nut portion 24 (the top surface 18 of the lock nut body 14) to the ring-shaped groove portion 20. Are provided.

  A balance adjusting set screw 46, which will be described later, is inserted into the screw holes 38 for balance adjustment from the top surface 18 side and screwed together. The axial length of the balance adjustment screw hole 38 is longer than the axial length of the balance adjustment set screw 46.

  Further, after the balance adjustment set screw 46 is inserted into the lock adjustment screw hole 38 and screwed into the lock nut main body 14, the balance adjustment screw hole 38 is inserted into the balance adjustment screw hole 38. A vibration control screw plug 48, which will be described later, is inserted and screwed together.

Then, next, FIG. 1, FIG. 2, FIG. 3 and FIG. 4, FIG. 5 are shown about an example of the rotation balance adjustment structure of the main shaft which adjusts the rotation balance of the main shaft 50 of a machine tool using the lock nut 10 mentioned above. The following will be described with reference to FIG.
That is, the main shaft rotation balance adjusting structure 100 according to the present embodiment shown in FIGS. 1 to 3 includes, for example, a hollow main shaft 50. The main shaft 50 is rotatably supported by a plurality of bearings 60 at, for example, a thick-walled cylindrical housing 70 at a plurality of axially intermediate portions and both side portions. As the bearing 60, for example, a rolling bearing that receives a radial load and a thrust load in at least one direction such as an angular ball bearing, a deep groove ball bearing, or a tapered roller bearing is used.
The housing 70 is fixed to a machine tool body (not shown) such as a spindle head (not shown) or a spindle head (not shown). In the housing 70, for example, a built-in type electric motor (not shown) as a driving device for rotating the main shaft 50 is disposed. The electric motor (not shown) includes a rotor (not shown) disposed on the outer periphery of the main shaft 50 and a stator (not shown) provided on the inner periphery of a housing (not shown) around the motor. Has been.

The main shaft 50 includes a male screw portion 50A on the outer peripheral surface thereof, and the female screw portion 12 of the lock nut body 14 described above is screwed into the male screw portion 50A.
In the present embodiment, the inner ring 62 of the bearing 60 is pressed and fixed by the seat surface 16 of the lock nut body 14. That is, as shown in FIG. 1, the tightening set screws 40 are respectively inserted into the plurality of tightening insertion holes 34 of the lock nut main body 14. In this case, particularly, as shown in FIG. 2, the tightening set screw 40 has its head portion 42 fitted in the counterbore hole portion 36, and the screw portion 44 a of the shaft portion 44 is screwed into the screw hole 32 for tightening. It is to be combined.

  When the set screw 40 for tightening is tightened, the interval between the ring-shaped groove portion 20 and the slit groove portion 26 is forcibly narrowed, and the first lock nut portion 22 and the second lock nut portion 24 are caused by their elastic restoring force. The flank of the first female screw portion 12a and the second female screw portion 12b increases the surface pressure of the main shaft 50 with respect to the male screw portion 50A, respectively, and the locking action of the lock nut body 14 with the female screw portion 12 becomes stronger. .

  Further, in this embodiment, as shown in FIG. 1, a balance adjustment set screw 46 is inserted into the screw hole 38 for balance adjustment of the lock nut body 14 from the top surface 18 side and screwed. In particular, as shown in FIG. 3, the balance adjustment set screw 46 has a screw portion 46 a that is pressed against the side surface 17 opposite to the seat surface 16 of the first lock nut portion 22. It is screwed into the screw hole 38 for balance adjustment.

  By mounting the balance adjustment set screw 46 in the plurality of balance adjustment screw holes 38, the rotation system including the main shaft 50 is prevented from rattling in the radial direction, and the rotation balance of the main shaft 50 is adjusted. That is, the balance adjustment set screw 46 corrects the deviation of the center of gravity of the rotating system including the main shaft 50 from the main shaft rotation center axis. In this case, among the plurality of balance adjustment screw holes 38, the balance adjustment screw hole 38 is positioned in a direction opposite to the direction in which the center of gravity of the rotation system including the main shaft 50 is shifted with respect to the rotation center axis of the main shaft 50. By mounting the balance adjusting set screw 46 on the center axis, the deviation of the center of gravity of the rotating system including the main shaft 50 from the main shaft rotation center axis is corrected.

  Further, in this embodiment, as shown in FIG. 3A, the balance adjustment set screw 46 is inserted into the balance adjustment screw hole 38 and screwed together, and then the balance adjustment set screw 46 is engaged. A vibration control screw plug 48 is inserted into and screwed into the screw hole 38 for balance adjustment so as to close the screw hole 38. The vibration control screw plug 48 has a slit 48a at the head, and a screw portion 48b is screwed into the screw hole 38 for balance adjustment. In this embodiment, the damping screw plug 48 is formed of a material having elasticity such as polycarbonate fiber and having impact resistance.

  When the vibration control screw plug 48 is attached to the balance adjustment screw hole 38 to which the balance adjustment set screw 46 has already been attached, vibration during rotation of the main shaft 50 is further suppressed. That is, the vibration of the rotating system including the main shaft 50 is further reduced by the cooperative action of the balance adjusting set screw 46 and the damping screw plug 48.

  In this case, the balance adjusting screw hole 38 is closed by the damping screw plug 48. That is, since the balance adjustment screw hole 38 is in a so-called plugged state, the noise is caused by, for example, wind noise compared to the case where the balance adjustment screw hole 38 is in a non-closed state. Is reduced, noise during high-speed rotation of the main shaft 50 can be suppressed, and noise can be reduced.

  In the embodiment shown in FIGS. 1 to 3 as described above, the fixed member such as the bearing 60 that rotatably supports the main shaft 50 can be positioned and fixed by using the lock nut 10 described above. The rotation balance of the rotation system including 50 can be adjusted as appropriate. That is, the lock nut 10 according to the present embodiment is suitable for use as a positioning component that corrects deformation such as parallelism and deflection of the spindle 50 of a machine tool that rotates at high speed.

6 (A) is a front schematic view showing another example of the lock nut body, and FIG. 6 (B) is a BB cross-sectional schematic view of FIG. 6 (A).
Compared with the lock nut main body 14 shown in FIG. 5, the lock nut main body 15 shown in FIG. 6 has a plurality of notch grooves 23 parallel to the axial direction of the lock nut main body 15, particularly in a part of the female screw portion 12. A plurality of screw holes 27 for tightening in a direction orthogonal to the axial direction of the lock nut main body 15 and communicating from the outer peripheral surface of the lock nut main body 15 to the cutout groove portion 23. The difference is that a rocking metal 25 made of an elastic metal material such as brass is inserted. A tightening set screw 40 is inserted into and screwed into the tightening screw hole 27. The lock nut body 15 has engagement holes 39 made of a plurality of concave grooves with a predetermined interval in the circumferential direction of the outer peripheral surface thereof. These engagement holes 39 are for engaging a dedicated spanner (not shown) such as a hook spanner used when the lock nut body 15 is attached to the main shaft 50 shown in FIG.
After the lock nut main body 15 shown in FIG. 6 is screwed onto the male screw portion 50A of the main shaft 50 and then attached, the locking metal 25 presses the flank surface of the male screw portion 50A of the main shaft 50. The function of preventing the locking nut body 15 from loosening acts.
Also in the lock nut main body 15 shown in FIG. 6, the balance adjustment set screw 46 and the vibration control screw are inserted into the screw holes 39 for balance adjustment arranged in the circumferential direction of the top surface 18 of the lock nut main body 15. By mounting the plug 48, the same operation and effect as the above-described embodiment are obtained.

It is principal part sectional solution figure which shows an example of embodiment which concerns on this invention. FIG. 2 is an enlarged illustrative view showing details of a part A in FIG. 1. FIG. 3A is an enlarged illustrative view showing the details of the portion B in FIG. 1, and FIG. 3B is a perspective illustrative view of a damping screw plug. It is a perspective view solution figure which shows a lock nut main body. (A) of FIG. 5 is a front schematic view of the lock nut body, (B) of FIG. 5 is a BB cross-sectional schematic view of (A) of FIG. 5, (C) of FIG. It is CC sectional illustration of FIG. 6 (A) is a front schematic view showing another example of the lock nut body, and FIG. 6 (B) is a BB cross-sectional schematic view of FIG. 6 (A).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Lock nut 12 Female thread part 12a 1st female thread part 12b 2nd female thread part 14 Lock nut main body 16 Seat surface 18 Top surface 20 Ring-shaped groove part 22 1st lock nut part 24 2nd lock nut part 26 Slit groove part 28, 30 32 Tightening screw hole 34 Tightening insertion hole 36 Counterbore hole 38 Balance adjustment screw hole 40 Tightening set screw 42 Head of tightening set screw 44 Shaft part of tightening set screw 44a Tightening set screw shaft 44a Threaded portion 46 Balance adjusting set screw 48 Damping screw plug 50 Machine tool main shaft 50A Main shaft male screw portion 60 Bearing 70 Housing 100 Main shaft rotational balance adjusting structure

Claims (2)

A lock nut that is screwed into a male screw portion of a main spindle of a machine tool and positions and fixes a fixed member attached to the main spindle.
A lock nut body having a female threaded portion that is screwed onto a male threaded portion of the main shaft on its inner peripheral surface;
A seating surface formed on one end side of the lock nut body in the axial direction and pressing the fixed member in the axial direction of the main shaft;
A top surface formed on the other end side of the lock nut body in the axial direction;
A plurality of screw holes for balance adjustment arranged at predetermined intervals in the circumferential direction of the top surface of the lock nut body and extending from the top surface in the axial direction of the lock nut body;
A balance adjusting set screw that is mounted on the balance adjusting screw hole from the top surface side of the lock nut body and adjusts the rotational balance of the spindle, and a balance adjusting screw on which the balance adjusting set screw is mounted. A lock nut, wherein the lock nut is mounted in a hole so as to close the screw hole for balance adjustment, and includes a vibration control screw plug for reducing vibration during rotation of the main shaft.   The rotation balance adjustment structure of the main shaft is characterized by adjusting the rotation balance of the main shaft by positioning and fixing the fixed member attached to the main shaft by the lock nut according to claim 1.

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